diff options
Diffstat (limited to 'lib/libc/i386/string/memset.S')
| -rw-r--r-- | lib/libc/i386/string/memset.S | 93 |
1 files changed, 93 insertions, 0 deletions
diff --git a/lib/libc/i386/string/memset.S b/lib/libc/i386/string/memset.S new file mode 100644 index 000000000000..2dcba4302a69 --- /dev/null +++ b/lib/libc/i386/string/memset.S @@ -0,0 +1,93 @@ +/* + * Copyright (c) 1993 Winning Strategies, Inc. + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. All advertising materials mentioning features or use of this software + * must display the following acknowledgement: + * This product includes software developed by Winning Strategies, Inc. + * 4. The name of the author may not be used to endorse or promote products + * derived from this software without specific prior written permission + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR + * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. + * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT + * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF + * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ + +#if defined(LIBC_RCS) && !defined(lint) + .text + .asciz "$FreeBSD$" +#endif /* LIBC_RCS and not lint */ + +#include <machine/asm.h> + +/* + * memset(void *b, int c, size_t len) + * write len bytes of value c (converted to an unsigned char) to + * the string b. + * + * Written by: + * J.T. Conklin (jtc@wimsey.com), Winning Strategies, Inc. + */ + +ENTRY(memset) + pushl %edi + pushl %ebx + movl 12(%esp),%edi + movzbl 16(%esp),%eax /* unsigned char, zero extend */ + movl 20(%esp),%ecx + pushl %edi /* push address of buffer */ + + cld /* set fill direction forward */ + + /* + * if the string is too short, it's really not worth the overhead + * of aligning to word boundries, etc. So we jump to a plain + * unaligned set. + */ + cmpl $0x0f,%ecx + jle L1 + + movb %al,%ah /* copy char to all bytes in word */ + movl %eax,%edx + sall $16,%eax + orl %edx,%eax + + movl %edi,%edx /* compute misalignment */ + negl %edx + andl $3,%edx + movl %ecx,%ebx + subl %edx,%ebx + + movl %edx,%ecx /* set until word aligned */ + rep + stosb + + movl %ebx,%ecx + shrl $2,%ecx /* set by words */ + rep + stosl + + movl %ebx,%ecx /* set remainder by bytes */ + andl $3,%ecx +L1: rep + stosb + + popl %eax /* pop address of buffer */ + popl %ebx + popl %edi + ret |